1. Field of the Invention
The present invention relates to a work-transporting robot provided between a plurality of press machines; particularly, the present invention relates to a synchronous control device for a plurality of robots.
2. Description of the Related Art
Conventionally known are press systems where pressing by a plurality of press machines occurs by transporting a work item in sequence using a work transport line. The work transport line involves a plurality of robots, a material supply device at an upstream side, a product removal device at a downstream side, and a plurality of intermediate stages.
Each robot transports a work item in a sequential manner between the intermediate stages. Each robot, the material supply device, and the product removal device are conventionally operated in an electronically linked manner, as will be described. During operation, each of the robots travels to a work retrieve position, from a home position, retrieves the work item, advances to a work release position, releases the work item, and returns to the home position.
During conventional operation, the position of the robots is matched at both a midpoint in the advance motion and the return motion. The midpoints are also linked to the motion of the material supply device and the product removal device, as will be explained. When each of the robots reaches the return midpoint, the corresponding press machines are activated and pressing is conducted.
During the advance and the return motion, a transporting speed for each of the robots may differ as a result in several factors. These factors include, differences in the weight of each work item, differences in the advance and return motions, and differences in retrieve and release motions. Thus, during adjustment to the press machines, robots, work transport line, or product removal device, each of the robots must be operated alone in order to avoid interference with adjacent robots or other devices.
Referring now to FIG. 6, a conventional flow control diagram for the work transport line includes a master board 17 linking a programmable controller 18 to three robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2. Additional conventional links to the material supply device (not shown) and the material removal device (not shown) are omitted for clarity.
Each robot 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 includes a programmable controller 16, a servo amp 15 and a servo motor 14 each in electronic communication with the other. Each robot 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 is linked to and controlled by programmable controller 18, through corresponding programmable controller 16. Electronic communications pass from programmable controller 16, by corresponding servo amp 15, to servo motor 14. Each servo motor 14 acts as a drive source for each corresponding robot 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 through a mechanical construction member (not shown).
During conventional linked operation, programmable controller 18 signals each robot 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2, through corresponding programmable controllers 16, to go to the corresponding work retrieve positions, retrieve the work items, and advance to the advance midpoints and wait. Once programmable controllers 18, 16 confirm that all robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 have reached the advance midpoints, each robot 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 advances to the corresponding work release position and releases the work items.
After releasing the work items, robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 return to the corresponding return midpoints and wait. Once programmable controllers 18, 16 confirm that all robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 have reached the corresponding return midpoints, all robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 wait for further signals from programmable controller 18. The return midpoint is also a home position for robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2. When robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 have reached the corresponding return midpoints, the corresponding press machines are activated. Repetition of the above described conventional process advances corresponding work items through the press system (not shown).
Using the conventional process, only the midpoint in the advance and the midpoint in the return are matched for corresponding robot 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2. As a result, the general movements of robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 are not continuously synchronized.
During adjustment, exchange of dies, or other maintenance activity conducted on the press system (not shown), robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 are operated individually in an inching operation (not shown). Since adjacent robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2 are not synchronized, the inching operation is conducted by individual inching movements (not shown). In this case, to avoid interference between adjacent robots 3axe2x80x2, 3bxe2x80x2, and 3cxe2x80x2, the range of inching movement is limited. As a result, adjustment, exchange of dies, or other maintenance activity is complex and time consuming thereby increasing operating costs.
It is an object of the present invention to provide a synchronous control device for a robot.
It is another object of the present invention to provide a synchronous control device to synchronize the operation of multiple work-transporting robots without matching the position of the robots at a point.
It is another object of the present invention to provide a synchronous control device adaptable to synchronize an inching or linked operation of multiple robots.
It is another object of the present invention to provide a synchronous control device for multiple robots that minimizes the danger of interference between adjacent robots during inching or linked operation.
A synchronous control device receives expansion data describing robot movement, stores the expansion data in a storage element, and in accordance with an internal clock or encoder equivalent, outputs the expansion data to a positioning controller through an output element to continuously control robot movement.
According to an embodiment of the present invention there is provided a synchronous control device comprising: an internal clock being of a type equivalent to a speed of an outside element, means for storing data characterizing a path and the speed of the outside element, means for outputting the data to a positioning controller in accordance with the internal clock, and the positioning controller receiving the data and controlling the outside element, whereby the outside element is continuously synchronized with the data.
According to another embodiment of the present invention there is provided a synchronous control device, comprising: means for storing data characterizing a path of a robot, a clock being of a type equivalent to a speed of said robot, means for outputting the data to a positioning controller in accordance with the clock, and the positioning controller commanding a control source for the robot, whereby the robot is continuously synchronized with the data.
According to another embodiment of the present invention there is provided a synchronous control device wherein: the clock is replaced with an encoder signal detecting a crank position of the robot.
According to another embodiment of the present invention there is provided a synchronous control device for a robot, being a synchronous control device for a work-transporting robot provided between press machines and having a drive source, comprising: an internal clock being of a type equivalent to a motion speed of the robot, a positioning controller being of a type which outputs a command signal to a drive source for the robot, means for storage being of a type which stores data describing a path of the robot, and means for output being of a type which outputs the data to the positioning controller in accordance with the internal clock.
According to another embodiment of the present invention there is provided a synchronous control device, wherein: the internal clock is replaced with a signal of an encoder detecting a crank angle of a press machine.
According to another embodiment of the present invention there is provided a synchronous control device, wherein: the motion speed of the robot is a work transport speed.
According to another embodiment of the present invention there is provided a synchronous control device, wherein: the drive source of the robot is a servo amp controlling a servo motor.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.